Sustainable Recycling of Silicon Solar Modules

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A major obstacle on the horizon for sustainable solar technologies is life-cycle management of solar modules. As module deployment expands rapidly, so will module wastes. The International Renewable Energy Agency estimates that end-of-life modules will total 78 million metric tons by 2050. With a successful project, the proposed recycling technology will become technically scalable, financially profitable, and environmentally sustainable for terawatt-scale deployment of silicon modules. The project lays down the technical foundation for a new recycling industry projected to be worth billions of dollars by 2050. The investigators have already demonstrated a two-step recycling process to extract all the valuable, bulky, and toxic materials from silicon modules including solar-grade silicon, silver, aluminum, glass, lead, copper, and tin. In this project, the researchers will: 1) develop a more simplified recycling process than the one already demonstrated; 2) improve the silver recovery rate to over 95%; 3) identify a low-cost anode for metal recovery by electrowinning; 4) verify that the recovered silicon meets the specifications of solar-grade silicon; 5) modify the recycling process for new commercial silicon solar cells; 6) explore a solar module backsheet reclamation process, and 7) dissolve the ethylene vinyl acetate layer in sodium hydroxide. What differentiates the proposed recycling technology is that it maximizes the revenue from recycling by recovering all the valuable, bulky, and toxic materials in silicon modules. These materials are raw materials to the solar industry worth $12.43/module today. The current recycling process recovers only the bulky materials worth $3.42/module, which is far below the actual cost of recycling. The proposed technology is targeted to enable profitable recycling.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.